Various methods have been used to form nitrosyl fluoride (NOF). One known method is to add a nitrite directly to an amine solution in hydrogen fluoride (HF). The direct addition of the nitrite to the HF solution of amine triggers a highly exothermic reaction which involves the formation of an unstable intermediate diazonium salt. Such salts are prone to decompose in a runaway reaction, producing safety hazards.
Attempts have also been made at producing NOF as a separate solution. The proposed processes have not proven satisfactory, as they generally fail to implement specific design provisions to deal with yield and operational problems, and typically, have been performed as a batch procedure. The batch makeup of NOF in HF is very exothermic. Local hotspots often account for yield losses of 3% or more, and as the volatile nitrite becomes a concentrated solution, the conversion by-products can contribute to high corrosion rates of the equipment used in the reaction.
When NOF solution is produced by a batch method, the addition of nitrite solids to anhydrous HF can generate a substantial amount of HF vapor. This HF vapor alters the material balance of the components and makes further processing difficult. Thus, vapor loss control equipment is needed under these circumstances to capture the HF released and prevent alteration of the material balance.
Batch processes for the production of NOF proceed by the incremental addition of nitrite to HF. Thus, there is no steady-state reaction mixture with the result that the reaction environment is continuously varying. In turn, this produces safety and containment engineering problems, the solutions of which have proven difficult and expensive.
Therefore a need exists for an alternative method of producing NOF which is safer to use, permits higher yields, improves process control, and reduces by-product corrosivity problems.